1. Field of the Invention
The present invention relates to vehicles and more particularly, vehicle control directed to eco-driving.
2. Description of the Prior Art
In order to reduce the emissions and the energy consumption of vehicles, car manufacturers develop more environmentally friendly vehicles, notably electric vehicles, hybrid vehicles, or thermal engine sizing. However, it is also possible to limit the energy consumption and the emissions by reducing vehicle users to more ecological driving, also referred to as eco-driving. Eco-driving is a general term that designates improved energy-efficient driving, that is optimization of the energy required for completing a trip in a given time interval.
In order to notify a driver of the quality of driving, a first solution developed is informing the driver about instantaneous fuel consumption. Patent applications DE-19,901,532 A and KR-100,520,941 B1 disclose methods of calculating the momentary fuel consumption. Similarly, other improvements involve information given to the driver about momentary or cumulative emissions. For example, patent application EP-2,166,309 A illustrates this type of technique. These two data (consumption, emissions), alone or combined, do not enable knowing if driving can be optimized from an ecological point of view. Indeed, the driver cannot compare the data displayed with values that would correspond to an eco-driving.
To overcome this problem, patent application EP-1,973,078 A1 describes an energy consumption determination method that compares the current energy consumption for a given trip with a previous energy consumption recorded for the same trip. To compare the data, this method requires the existence of previous trips and a record of this information. Therefore, the driver cannot be informed about the ecological character of driving for a trip that has not been traveled. Furthermore, this method does not allow external driving constraints (road signs, traffic, etc.) to be taken into account. In fact, if the previous trip was recorded under ideal traffic conditions (for example without traffic stops), and if the current traffic conditions are less good, the information given to the driver is not representative of the ecological character of driving under the current external conditions.
Other developments relate to the calculation of an ideal energy consumption, so to provide a point of reference for comparison with the real consumption. Patent application EP-2,147,285 A1 describes a method implementing such a comparison. For this method, a signal is generated when the energy consumption is different from the ideal consumption. However, this method involves the same drawback as the aforementioned method. It does not allow the external driving conditions to be taken into account.
Patent application EP-2,311,683 A1 describes another method allowing the driver to know whether his or her driving can be referred to as eco-driving. This method can be used for a hybrid vehicle. For this method, one determines whether the driving parameters are in an ecological zone, a hybrid ecological zone or a non-ecological zone. Considering the limitation to these three zones only, it is not possible to precisely quantify the driving. Furthermore, these zones are defined by predetermined thresholds and it is therefore not possible to take the external driving conditions into account.